Nov 21, · Essay on democracy with quotations. Sample essay questions for an inspector calls: ap lang synthesis essay ielts essay topic business, essay about sardar vallabhbhai patel magh bihu essay in english preface to lyrical ballads essay questions badminton club Essay guru nanak dev ji in english essay on technological development ielts simon sample essays essay type questions on romantic age. Essay writing mcqs with answers discursive essay secondary school, english essay informal letter format spm, exchange rate essay muet marriage life @ who essay person to my arranged essay! scientific good write a May 07, · A comprehensive database of more than 16 cell cycle quizzes online, test your knowledge with cell cycle quiz questions. Our online cell cycle trivia quizzes can be adapted to suit your requirements for taking some of the top cell cycle quizzes
DNA Forms: 7 Main Forms of DNA | Biochemistry
The most common form of DNA which has right handed helix and proposed by Watson and Crick is called B-form of DNA or B-DNA. In addition, the DNA may be able to exist in other forms of double helical structure. These are A and C forms of double helix which vary from B- form in spacing between nucleotides and number of nucleotides per turn, rotation per base pair, vertical rise per base pair and helical diameter Table 5.
Structure of B-form of DNA has been proposed by Watson and Crick. It has antiparallel double helix, rotating clockwise right hand and made up of sugar- phosphate back bone combined with base pairs or purine-pyrimidine. The base pairs are perpendicular to longitudinal axis of the helix. The base pairs tilt to helix by 6. The B-form of DNA is metabolically stable and undergo changes to A, C or D forms depending on sequence of nucleotides and concentration of excess salts.
It contains eleven base pairs as compared to ten base pairs of B-DNA which tilt from the axis of helix by Due to this displacement the depth of major groove increases and that of minor groove decreases. The A-form is metastable and quickly turns to the D-form. As compared to A-and B-DNA, in C-DNA the number of base pairs per turn is less i.
The base pairs show pronounced negative tilt by 7. The D-form of DNA is found rarely as extreme vanants. Total number of base pairs per turn of helix is eight.
Therefore, it shows eight-fold symmetry. This form is also called poly dA-dT and poly dG-dC form. There is pronounced negative tilt of base pairs by the base pairs are displaced backwardly with respect to the axis of DNA helix. InRich and coworkers at MIT U. obtained Z-DNA by artificially synthesizing d Dna replication essay questions and answers 3 molecules in the form of crystals.
They proposed dna replication essay questions and answers left handed synistral double helix model with zig-zag sugar-phosphate back bone running in antiparallel direction. Therefore, this DNA has been termed as Z-DNA. The Z-DNA has been found in a large number of living organisms including mammals, protozoans and several plant species. b The Z-DNA contains zig-zag sugar phosphate back bone as compared to regular back bone of the B-DNA.
c The repeating unit in Z-DNA is a dinucleotide due to alternating orientation of sugar residues, whereas in B-DNA the repeating unit is a mononucleotide, and sugar molecules do not have the alternating orientation.
d In the Z-DNA one complete turn contains 12 base pairs of six repeating dinucleotide, while in B-DNA one full turn consists of 10 base pairs i. the 10 repeating units. e Dna replication essay questions and answers to the presence of high number 12 of base pairs in one turn of Z-DNA, the angle of twist per repeating unit i, dna replication essay questions and answers. dinucleotide is 60° as compared to 36° of B-DNA molecule, dna replication essay questions and answers.
Almost all the organisms contain double stranded DNA except a few viruses such as bacteriophage φ × which consists of single stranded circular DNA. It becomes double stranded only at the time of replication. a The dsDNA absorbs wavelength Å of ultra violet light constantly from 0 to 80°C, thereafter rise sharply, whereas in ssDNA absorption of UV light increases steadily from 20° to 90°C.
b The dsDNA resists the action of formaline due to closed reactive site, while the ss DNA does not resist it due to exposed reactive sites. c Base pair composition in dsDNA is equal i. d The dsDNA always remains in linear helical form, while the ssDNA remains in circular form; however, it becomes double stranded only during replication i. replicative form. Almost in all the prokaryotes and a few viruses, the DNA is organised in the form of closed circle.
The two ends of the double helix get covalently sealed to form a closed circle. Thus, a closed circle contains two unbroken complementary strands. Sometimes one or more nicks or breaks may be present on one or both strands, for example DNA of phage PM2 Fig. Besides some exceptions, the covalendy closed circles are twisted into super helix or super coils Fig. This histone like proteins appear to help the organization of bacterial DNA into a coiled chromatin structure with the result of nucleosome like structure, folding and dna replication essay questions and answers coiling of DNA, and association of DNA polymerase with nucleoids.
Several histones like DNA binding proteins have been described in bacteria Table 5, dna replication essay questions and answers. These nucleoid-associated proteins include HU proteins, IHF, dna replication essay questions and answers, protein H1, Fir A, H-NS and Fis. In archaeobacteria e. Archaea the chromosomal DNA exists in protein-associated form. Histone like proteins has been isolated from nucleoprotein complexes in Thermoplasma acidophilurn and Halobacterium salinanim.
Thus, the protein associated DNA and nucleosome like structures are detected in a variety of bacteria. If the helix coils clockwise from the axis the coiling is termed as positive or right handed coiling.
In contrast, if the path of coiling is anticlockwise, dna replication essay questions and answers, the coil is called left handed or negative coil, dna replication essay questions and answers.
The two ends of a linear DNA helix can be joined to form each strand continuously. Dna replication essay questions and answers, if one of ends rotates at ° with respect to the other to produce some unwinding of the double helix, the ends are joined resulting in formation of a twisted circle in opposite sense i.
opposite to unwinding direction. Such twisted circle appears as 8 i. it has one node or crossing over point. If it is twisted at ° before joining, the resulting super helix will contain two nodes Fig. The enzyme topoisomerases alter the topological form i. super coiling of a circular DNA molecule. Type I topoisomerases e. Type II topoisomerases need energy to unwind the DNA molecules resulting in the introduction of super coils. One of type II isomerases, the DNA gyrase, is apparently responsible for the negatively super coiled state of the bacterial chromosome.
Super coiling is essential for efficient replication and transcription of prokaryotic DNA. The bacterial chromosome is believed to contain about 50 negatively super coiled loops or domains. Each domain represents a separate topological unit, the boundaries of which may be defined by the sites on DNA that limit its rotation. MicrobiologyBiochemistrydna replication essay questions and answers, Nucleic AcidsDNAForms of DNA. Top Menu BiologyDiscussion.
com Follow Us On: Facebook Twitter Google Plus Publish Now. Navigation Home Static Main Menu Home Questions and Answers Forum Share Your Knowledge Content Quality Guidelines Disclaimer Privacy Policy Contact Us.
Related Articles: Essay on DNA: Meaning, Features and Forms Genetics Watson-Crick Model of DNA Genetics. Genetic Engineering: Definition and Strategies Genetics. Characteristics of Fungi Microbiology. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Answer Now and help others. Answer Now. Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top. Give examples. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits.
Do not sell my personal information. Cookie Settings Accept. Manage consent. Close Privacy Overview This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website.
We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience. Necessary Necessary. Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.
Cookie Duration Description cookielawinfo-checkbox-analytics 11 months This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics", dna replication essay questions and answers.
cookielawinfo-checkbox-functional 11 months The cookie is set by GDPR cookie consent to record the user consent for dna replication essay questions and answers cookies in the category "Functional". cookielawinfo-checkbox-necessary 11 months This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary". cookielawinfo-checkbox-others 11 months This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance 11 months This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
dna replication practice q
, time: 3:07Essay on neat and clean! essay on incredible india in english! ? Essay poem writer
May 07, · A comprehensive database of more than 16 cell cycle quizzes online, test your knowledge with cell cycle quiz questions. Our online cell cycle trivia quizzes can be adapted to suit your requirements for taking some of the top cell cycle quizzes The C-Form DNA (C-DNA): The C-form of DNA is found at 66% relative humidity in the presence of lithium (Lit+) ions. As compared to A-and B-DNA, in C-DNA the number of base pairs per turn is less i.e. 28/3 or 9 1/3. The base pairs show pronounced negative tilt by °. 4. The D-Form of DNA (D-DNA): The D-form of DNA is found rarely as extreme Essay guru nanak dev ji in english essay on technological development ielts simon sample essays essay type questions on romantic age. Essay writing mcqs with answers discursive essay secondary school, english essay informal letter format spm, exchange rate essay muet marriage life @ who essay person to my arranged essay! scientific good write a
No comments:
Post a Comment